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Finding the Fourth Proportional to 122.15, 168.58 and 78.61

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Solution

The fourth proportional to 122.15, 168.58 and 78.61 is: 108.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.15 : 168.58 = 78.61 : x
  2. Step 2: Convert to fraction form
    122.15/168.58 = 78.61/x
  3. Step 3: Cross multiply
    122.15x = 168.58 × 78.61
  4. Step 4: Simplify right side
    122.15x = 13,252.07
  5. Step 5: Solve for x
    x = 13,252.07/122.15
  6. Step 6: Final answer
    x = 108.49

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.